How to Disable Standby Mode
Standby mode (also called Auto-Lock) is when your phone screen automatically darkens when you’re not touching or actively using your phone. This can cause problems when running the game timer app so it should be (at least temporarily) disabled while using the game timer.
iPhone
To turn off the screensaver feature on your iPhone, go to Settings > Display & Brightness > Auto-Lock and then turn it off or set it to a longer duration, such as five minutes. (Return to Game Timer App)
Android
To turn off the auto-screen lock on an Android device, go to Settings > Security > Screen Lock and select “None” or “Swipe” to disable the lock. This will prevent the screen from locking automatically. (Return to Game Timer App)